Circuit line widths required for semiconductor devices are yearly becoming finer with higher integration of the semiconductor devices. In order to form a desired circuit pattern in a semiconductor device, a high-precision original pattern is needed. Here, electron beam (EB) lithography technology has excellent resolution essentially and is used for production of high-precision original patterns.
For example, since an EB (electron beam) lithography apparatus in a multibeam lithography scheme can radiate many beams at once by using multibeams for lithography, throughput can be drastically improved as compared with the case of performing lithography with one electron beam. In such an EB lithography apparatus, for example, an electron beam released from an electron gun is caused to pass through a mask having a plurality of holes to form the multibeams, which beams are caused to pass through a blanking aperture array (BAA) apparatus. In this stage, the beams individually undergo deflection control by the BAA apparatus, and deflected beams are radiated onto a shield to be shielded (blanked). Beams not deflected are radiated onto a sample. The beams not deflected undergo deflection control by a separate deflector from the BAA apparatus so as to be radiated to desired positions on the sample.
FIGS. 10A and 10B are schematic diagrams showing a configuration of a conventional BAA apparatus.
FIG. 10A shows a controlling circuit 1 that controls blanking operation of the BAA apparatus, driving circuits 2 that drive electrodes of the BAA apparatus, and apertures 3 for causing electron beams to pass through. As shown in FIG. 10A, the BAA apparatus includes an aperture array having the plurality of apertures 3. The aperture array in FIG. 10A has m×n apertures 3 arranged into an array (m and n are positive integers). The BAA apparatus is constituted of a semiconductor chip (BAA chip).
FIG. 10B shows a pattern structure of an electrode portion of one aperture 3 constituting the aperture array as seen from the above. Specifically, FIG. 10B shows lines 4a and 4b, via plugs 5a and 5b, and electrodes 6a and 6b which are provided near this aperture 3. The electrode 6a is a deflecting electrode for deflecting an electron beam passing through this aperture 3. The electrode 6b is a ground electrode to which a ground (GND) potential is applied. Hereafter, the electrode 6a is expressed as a “deflecting electrode” for convenience, and the electrode 6b is expressed as a “ground electrode” for convenience. The electrode 6a is also referred to as a blanking electrode, the electrode 6b is also referred to as an earth electrode.
In this BAA apparatus, the controlling circuits 1 and the driving circuits 2 are manufactured through a semiconductor manufacturing process. Meanwhile, the aperture array is generally manufactured through a MEMS (Micro Electro Mechanical Systems) manufacturing process since the electrode portion, that is, a portion of the electrode 6a and the electrode 6b is needed to be thick.
The controlling circuit 1 is constituted of a receiving circuit for receiving lithography data transferred from a calculator system at high speed, a delivering circuit that delivers the received data for deflection control at each aperture 3, and the like. The driving circuit 2 is constituted of a level converting circuit that converts an internal voltage level of an LSI (Large Scale Integrated circuit) into a voltage level needed for deflecting an electron beam by the deflecting electrode 6a, a buffer circuit that outputs a driving signal having the converted voltage level to actually drive the deflecting electrode 6a, and the like. The controlling circuit 1 and the driving circuits 2 manufactured through the semiconductor manufacturing process are tested, for example, by a scanning test circuit in the shipping test step of the LSI.
The deflecting electrode 6a is used for applying a voltage for deflection control of the electron beam. The aperture 3 is a hole formed in a semiconductor substrate such that the electron beam can pass through, and sandwiching the aperture 3, the deflecting electrode 6a and the ground electrode 6b which are MEMS electrodes are arranged. The deflecting electrode 6a is connected to the output of the driving circuit 2 at the lower layer via the via plug 5a and the line 4a. Meanwhile, the ground electrode 6b is connected to the ground potential via the via plug 5b and the line 4b. Examples of the lines 4a and 4b are metal lines such as aluminum lines.
In blanking, a voltage is applied between the deflecting electrode 6a and the ground electrode 6b, and the electron beam is deflected with an electric field generated in this way. To the deflecting electrode 6a, the voltage of the driving circuit 2 is only electrically applied, and it does not drive any other circuits. Therefore, in order to test the deflecting electrode 6a, direct contact with the deflecting electrode 6a is needed. However, since the size of the deflecting electrode 6a, which is tens of nanometers, is small, such direct contact with the deflecting electrode 6a for testing the deflecting electrode 6a is difficult.
Therefore, in inspection of the deflecting electrodes 6a, it is visually confirmed at the end of the MEMS process that the deflecting electrodes 6a are not peeled off, or it is tested whether the lines 4a and 4b make a short by measuring a current flowing between the lines 4a and 4b with the deflecting electrode 6a driven. However, this inspection cannot detect a failure in which the deflecting electrode 6a is open. Therefore, such an open failure of the deflecting electrode 6a is determined by implementing the BAA apparatus on a printed circuit board and actually mounting this board on an EB lithography apparatus to confirm whether the EB lithography apparatus can properly control electron beams.